The car could possibly use GPS, but even GPS could be a stretch in a self-driving car if there are different traffic signs indicated for a certain place. Steering could be made with voice recognition, ordering the car to turn left or right depending on the road. I don't know how exactly would this self-driving car turn out, but I know one thing for certain: don't market it in my country because drivers here are so unpredictable and aggressive in driving.
Actually the car will probably respond to them more quickly than a person would. That's their charm.
I don't see their benefit while travelling around the city and such as it is no necessary. Although when travelling on highways for more than a thousand kilometers they would be very useful.
Like I said, once this matures it will be a thing. A person driving a car will be optional someday.